Pneumatically adjustable apparatus for coating toner fusing belt substrate and method for using same

Abstract

An apparatus for enabling the uniform application of a layer of a coating composition to a tubular substrate includes a shaft, and upper and lower circular rim members of equal diameter that are concentrically attached to the shaft. A pneumatically inflatable tube disposed on each circular rim member has an outer diameter that is variable with changes in its internal pressure. A first flexible cylindrical sheet in contact with the inflatable tubes has parallel edges that form a first slit sufficiently wide to permit movement of the first sheet in response to pressure variation in the tubes. A second flexible cylindrical sheet surrounding the first cylindrical sheet has parallel edges that form a second slit sufficiently wide to permit movement of the second sheet also in response to pressure variation. The second slit is laterally displaced from the first slit, and the second cylindrical sheet has a diameter nearly equal to the specified diameter of the substrate. Each of the tubes is inflatable to a pressure sufficient to provide the substrate with a smooth cylindrical outer surface for uniform application of a coating.

1. With an apparatus comprising a vertical shaft; an upper horizontal circular rim member and a lower horizontal circular rim member of equal diameter, each said rim member being concentrically attached to said shaft and separated from one another by a distance at least equal to the length of the substrate; a pneumatically inflatable tube disposed on each said circular rim member, each said tube being provided with a pneumatic valve and having an outer diameter that is variable with changes in its internal pressure; a first flexible cylindrical sheet contacting and substantially surrounding each of said tubes, said first sheet having vertical edges parallel to one another and forming a first slit sufficiently wide to permit movement of said first sheet in response to variation in said internal pressure of said tubes; a second flexible cylindrical sheet contacting and substantially surrounding said first cylindrical sheet, said second sheet having vertical edges parallel to one another and forming a second slit sufficiently wide to permit movement of said second sheet in response to variation in said internal pressure of said tubes, said second slit being laterally displaced from said first slit, second cylindrical sheet having a diameter nearly equal to the specified diameter of the substrate; a process for coating a seamless tubular flexible cylindrical substrate having a specified length and a specified diameter, said process comprising:
 placing said seamless tubular flexible cylindrical substrate around said second flexible cylindrical sheet; 
 inflating said tubes to a pressure sufficient to provide the substrate with a smooth, uniform cylindrical outer surface; and 
 applying a coating composition to said outer surface of said substrate, thereby forming a uniform layer of said coating composition thereon. 
 
     
     
       2. The process of  claim 1  further comprising:
 drying said layer of said coating composition, thereby forming a dried layer on said substrate; 
 deflating said tubes to a pressure sufficiently low to enable removal of said dried layer, said substrate, and said second flexible cylindrical sheet from said apparatus; and 
 removing said dried layer, said substrate, and said second flexible cylindrical sheet from said apparatus. 
 
     
     
       3. The process of  claim 1  wherein said substrate comprises polyimide. 
     
     
       4. The process of  claim 1  wherein said applying said coating composition comprises ring coating said substrate. 
     
     
       5. The process of  claim 2  wherein said dried layer comprises a toner release layer.